1. Field of the Invention
The present invention relates to a display apparatus for displaying an image on the basis of a video signal and, more particularly, to a projection-type display apparatus for displaying an image on a reflection- or transmission-type screen, and a light modulation element array for a projection-type display apparatus.
2. Description of the Related Art
Currently, plasma display panels or liquid crystal panels have received a great deal of attention as compact, light weight, flat panel display apparatuses replacing CRT display apparatuses. The flat panel display apparatuses can be classified into self-emission type apparatuses which emit light by itself in a display operation and transmittance control type apparatuses which control the transmittance of light incident from an independent light source in the display operation. A plasma display panel belongs to the self-emission type apparatuses while a liquid crystal panel belongs to the transmittance control type apparatuses. Particularly, a display apparatus of the transmittance control type represented by a liquid crystal panel is considered as a most promising next-generation display apparatus, and techniques for this apparatus have been developed in a variety of practical fields.
A general liquid crystal panel is characterized in that a light beam which is linearly polarized using a polarizing plate is caused to be incident on a liquid crystal layer exhibiting birefringence or rotatory polarization, as represented by a twisted nematic (TN) liquid crystal described in the liquid crystal device handbook.
As shown in FIG. 1, a projection-type display apparatus 901 using such a liquid crystal panel comprises liquid crystal panels 911-R, 911-G, and 911-B respectively corresponding to red (R), green (G), and blue (B), a light source optical system having a light source 921 for irradiating light on the liquid crystal panels 911-R, 911-G, and 911-B and a parabolic condenser mirror 931 for collimating source light from the light source 921, and a projection optical system having a projection lens 941 for projecting the light selectively transmitted from the liquid crystal panels 911-R, 911-G, and 911-G onto a screen.
It is important for the projection-type display apparatus to improve brightness. From this viewpoint, attempts have been made such that a microlens array is arranged in the liquid crystal panel to increase the effective aperture ratio, or a polymer-dispersed liquid crystal which needs no polarizing plate is used.
In the projection-type display apparatus 901, source light is collimated using the parabolic condenser mirror and caused to be incident on the liquid crystal panels. In this case, the electrode portion and the like of the light source form a shade. This makes the angle distribution of light incident on the liquid crystal panels large, and a parallel light component is lost, as shown in FIG. 2. For this reason, the effect for increasing the effective aperture ratio cannot be sufficiently achieved even by arranging microlenses on the light incident axis side of the liquid crystal panel.